Materials useful as electrolytic solutes

ABSTRACT

The invention concerns novel ionic compounds with low melting point whereof the onium type cation having at least a heteroatom such as N, O, S or P bearing the positive charge and whereof the anion includes, wholly or partially, at least an ion imidide such as (FX 1 O)N − (OX 2 F) wherein X 1  and X 2  are identical or different and comprise SO or PF, and their use as solvent in electrochemical devices. Said composition comprises a salt wherein the anionic charge is delocalised, and can be used, inter alia, as electrolyte.

This application is a continuation of Ser. No. 09/390,642, filed Sep. 7,1999, now U.S. Pat. No. 6,365,301.

FIELD OF INVENTION

The present invention relates to ionic compositions having a high ionicconductivity, comprising a salt wherein the anionic charge isdelocalized, and their uses, such as an electrolyte.

BACKGROUND OF THE INVENTION

Room temperature molten salts, such as triethyl ammonium nitrate, havebeen known for a long time. This product is of no interest exceptbecause of the presence of a leaving proton on the cation, limiting theredux or acido-basic stability domain of the compound.Methyl-ethylimidazolium or butyl-pyridinium type compounds, associatedto the complex ion [Cl⁻,xAlCl₃] wherein 1<x<2, are also known. Thesecompounds, because of the presence of the aluminium chloride, arepowerful Lewis acids, hygroscopic and corrosive because they generatehydrochloric acid in the presence of humidity. Their electrochemicalstability domain is also limited by the anodic oxydation of the chlorideion on one side, and by the reduction of the aluminium ion on the otherside.

The use of anions usually stables associated to imidazolium orpyridinium type cations has been proposed, but the melting points arerelatively high. For example, 1-methyl-3-ethylimidazoliumhexafluorophosphate melts at 60° C., and1,2-dimethyl-3-propylimidazolium hexafluorophosphate melts at 65° C. Inaddition, these salts, although not hygroscopic, are neverthelesssoluble in water and can therefore be hardly prepared by ion exchange inwater unless longer alkyl substituents are used, which results in astrong reduction in conductivity and enhanced viscosity.

U.S. Pat. No. 5,827,602 describes salts with a melting point relativelylow, with a selection criteria being an anion volume higher than 100 Å³,thus allowing to obtain salts with high conductivity and hydrophobiccharacter. Most representative anions are thebis-trifluoromethanesulfonimidide, that has a calculated volume of 144Å³ with Hyperchem® program, or thetris-trifluoromethanesulfonylmethylide, which has a volume of 206 Å³.

SUMMARY OF THE INVENTION

The present invention is concerned with low melting point ioniccompounds, preferably lower than room temperature, wherein the cation isof the onium type and having at least one heteroatom such as N, O, S orP bearing the positive charge and wherein the anion comprises, in wholeor in part, at least one imidide ion of the type (FX¹O)N⁻(OX²F) whereinX¹ and X² are the same or different and comprise SO or PF. Morespecifically, the onium type cation comprises a compound of formula:

wherein

-   W is O, S or N, and wherein N is optionally substituted with R¹ when    the valence allows it;-   R¹, R³, R⁴ are the same or different and represent-   H;-   an alkyl, alkenyl, oxaalkyl, oxaalkenyl, azaalkyl, azaalkenyl,    thiaalkyl, thiaalkenyl, dialkylazo, each of these can be either    linear, branched or cyclic and comprising from 1 to 18 carbon atoms;-   cyclic or heterocyclic aliphatic radicals of from 4 to 26 carbon    atoms optionally comprising at least one lateral chain comprising    one or more heteroatoms;-   groups comprising several aromatic or heterocyclic nuclei, condensed    or not, optionally comprising one or more atoms of nitrogen, oxygen,    sulfur or phosphorous; and wherein two groups R¹, R³ or R⁴ can form    a cycle or a heterocycle of from 4 to 9 carbon atoms, and wherein    one or more R¹, R³ or R⁴ groups on the same cation can be part of a    polymeric chain;-   R² and R⁵ to R⁹ are the same or different and represent R¹, R¹O—,    (R¹)₂N—, R¹S—, R¹ being as defined above.

The invention further comprises an electrolytic composition comprisingat least one ionic compound as defined above in combination with atleast another component comprising a metallic salt, a polar polymerand/or an aprotic co-solvent.

DETAILED DESCRIPTION OF THE INVENTION

It has been found that onium-type cation salts as defined above, andpreferably the imidazolium, ammonium, sulfonium and phosphonium salts,associated to anions of the family represented by the general formula(FX¹O)N⁻(OX²F) as defined above allow to obtain liquid salts attemperatures equal or lower than those obtained with larger ions.Further, their conductivity is, in all instances, at the sametemperature, superior to that of the compounds described in U.S. Pat.No. 5,827,602. These liquid salts are hydrophobic even though the anionsize is small, comprised between 85 and 92 Å³, and thus, easily preparedby ion exchange in water, and can be handled without any particularprecaution. Unexpectedly, these salts show an oxydation stability equalto that of the bis(trifuoromethanesulfonimidide) ortris(trifluoromethanesulfonyl)methylide anions, and higher than thatobtained with anions of the tetrafluoroborate or hexafluorophoboratetype.

The compounds of the present invention can, in addition to the imidideanion mentioned above, comprise at least another anion selected fromCl⁻; Br⁻; I⁻; NO₃ ⁻; M(R¹⁰)₄ ⁻A(R¹⁰)₆ ⁻;R¹¹O₂ ⁻,[R¹¹ONZ¹]⁻,[R¹¹YOCZ²Z³]⁻, 4,5-dicyano-1,2,3-triazol, 3,5-bis(R_(F))-1,2,4-triazole,tricyanomethane, pentacyanocyclopentadiene,pentakis-(trifluoromethyl)cyclopentadiene, barbituric acid and Meldrumacid derivatives and their substitution products;

-   M is B, Al, Ga or Bi;-   A is P, As and Sb;-   R¹⁰ is a halogen;-   R¹¹ represents H, F, alkyl, alkenyl, aryl, arylalkyl, alkylaryl,    arylalkenyl, alkenylaryl, dialkylamino, alkoxy or thioalkoxy, each    having from 1 to 18 carbon atoms and being unsubstituted or    substituted with one or more oxa, thia, or aza substituents, and    wherein one or more hydrogen atoms are optionally replaced with    halogen in a ratio of 0 to 100%, and eventually being part of    polymeric chain;-   Y represents C, SO, S═NCN, S═C(CN)₂, POR¹¹, P(NCN)R¹¹, P(C(CN)₂R¹¹,    an alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl,    alkenylaryl having from 1 to 18 carbon atoms and optionally    substituted by one or more oxa, thia or aza; a dialkylamino group    N(R¹⁰)₂;-   Z¹ to Z³ representing independently R¹¹, R¹¹YO or CN, this group    being optionally part of a polymeric chain.

Another advantage of the compounds of the invention is the low cost ofthe starting anions, their preparation not requiring perfluoroalkylchemistry such as CF₃ or C₄F₉ for instance, the fluorine atoms presentin the compounds of the invention being derived from inorganic chemistryproducts, thus easily accessible. This economical aspect is particularlyimportant because the molten salts contain between 40 and 75% by weightof the anionic species, the remainder being the cationic species. Inaddition, the density of these liquids is close to 1.5, compared toabout 1 for the organic solutions, which requires more importantquantities of salts for all applications wherein a volume or a giventhickness are necessary, such as electrolyte films, chemical reactors,etc.

Another particularly important aspect of the present invention is thepossibility for these molten salts to dissolve other salts, inparticular metallic salts, such as lithium salts, to give highlyconductive solutions. In a similar manner, the molten salts, or theirmixtures with other metallic salts, are excellent solvents orplasticizers for a great number of polymers, in particular those bearingpolar or ionic functions. Liquid compounds as well as polymersplasticized by ionic mixtures behaving like solid electrolytes areapplicable in electrochemistry to generators of the primary or secondarytype, supercapacities, electrochromic systems, antistatic coatings, orelectroluminescent diodes. The non-volatility of the molten salts of theinvention, their thermal and electrochemical stability, and theirenhanced conductivity are important parameters for the fabrication ofdevices working at low temperature and not presenting the usualflammability risks associated with the use of conventional organicsolvents.

The molten salts of the invention are polar media of low volatility, andbecause of this, are capable of being used as solvents to perform agreat number of organic chemistry reactions, such as nucleophilic anelectrophilic substitutions, or anionic, cationic or radicalarpolymerisations. It is also possible to dissolve catalysts in suchmedia, in particular transition metal salts or rare earth saltseventually coordinated with ligands, to increase the catalyticproperties. Examples of such catalysts include bipyridines, porphyrines,phosphines, arsines. Organometallics like metallocenes are also includedas solutes that can present catalytic properties.

The non-volatility of the molten salts, their thermal stability andtheir non-miscibility with non-polar solvents like hydrocarbons, as wellas their hydrophobic character, are particularly advantageous toseparate the chemical reaction products. It is also possible to work indiphasic systems, the molten salts containing the catalyst and thereacting substrates being in solution in a hydrocarbon or non-misciblealiphatic ether. After the reaction, a simple decantation can separatethe organic phase containing the reaction product and the molten saltthat is purified by washing with a non-solvent such as water orhydrocarbon, and dried by simple in vacuo procedure.

The ammonium, phosphonium and sulfonium cations can have an opticalisomery and the molten salts containing them are chiral solventssusceptible or favoring the formation of enantiomeric excesses in thereactions performed in these media. Preferred cations for the presentinvention comprise the compounds of formula:

that include the imidazolium, triazolium, thiazolium, and oxazoliumderivatives; the compounds of formula

that include the trizolium, oxadiazolium, and thadiazolium; thecompounds of formula

preferably pyridinium derivatives

the compounds of formula

wherein

-   W is O, S or N, and wherein N is optionally substituted with R¹ when    the valence allows it;-   R¹, R³, R⁴ are the same or different and represent-   H;-   an alkyl, alkenyl, oxaalkyl, oxaalkenyl, azaalkyl, azaalkenyl,    thiaalkyl, thiaalkenyl, dialkylazo, each of these can be either    linear branched or cyclic and comprising from 1 to 18 carbon atoms;-   cyclic or heterocyclic aliphatic radicals of from 4 to 26 carbon    atoms optionally comprising at least one lateral chain comprising    one or more heteroatoms such as nitrogen, oxygen or sulfur;-   aryl, arylalkyl, alkylaryl and alkenyaryl of from 5 to 26 carbon    atoms optionally comprising one or more heteroatoms in the aromatic    nucleus;-   groups comprising several aromatic or heterocyclic nuclei, condensed    or not, optionally comprising one or more atoms of nitrogen, oxygen,    sulfur or phosphorous; and wherein two groups R¹, R³ or R⁴ can form    a cycle or a heterocycle from 4 to 9 carbon atoms, and wherein one    or more R¹, R³ or R⁴ groups on the same cation can be part of a    polymeric chain;-   R² and R⁵ to R⁹ are the same or different and represent R¹, R¹O—,    (R¹)₂N—, R¹S—, R¹ being as defined above.

R¹, R³ and R⁴ groups can bear groups active in polymerization such asdouble bonds or epoxides, or reactive functions in polycondensations,such as OH, NH₂, or COOH. When the cations include double bonds, theycan be homopolymerized or copolymerized, for instance with vinylidenefluoride, an acrylate, a maleimide, acrylonitrile, a vinylether, astyrene, etc. Epoxide groups can be polycondensed or copolymerized withother epoxides. These polycations are particularly useful alone or in amixture with a solvent, including a molten salt of the present inventionand/or one or more lithium salt or a mixture of lithium and potassiumsalts as electrolyte in lithium batteries with a lithium anode or usinga cathode inserting the lithium at low potential such as titanium spinelor carbonated materials.

The invention further concerns an electrolytic composition comprising atleast one ionic compound comprising at least one anion and at least onecation as defined above in combination with at least another compoundcomprising a metallic salt, a polar polymer and/or an aproticco-solvent. A preferred cation of the metallic salt comprises theproton, an alkaline metal cation, an alkaline-earth metal cation, atransition metal cation, a rare earth metal cation, lithium beingparticularly preferred.

A preferred polar polymer comprises monomer units derived from ethyleneoxide, propylene oxide, epichlorohydrine, epifluorohydrine,trifluoroepoxypropane, acrylonitrile, methacrylonitrile, esters andamides of acrylic and methacrylic acid, vinylidene fluoride,N-methylpyrrolidone and polyelectrolytes of the polycation or polyanion.Finally, examples of preferred aprotic co-solvent include di-alkylicethers of ethylene glycol, diethylene glycol, triethylene glycol,polyethylene glycols of weight comprised between 400 and 2000; esters,in particular those of carbonic acid, linear or cyclics such asdimethylcarbonate, methyl-ethyl carbonate, diethylcarbonate, ethylenecarbonate, propylene carbonate; esters like γ-butyrolactone, nitrileslike glutaronitrile, 1,2,6-tricyanohexane, amides such asdimethylformamide, N-methylpyrrolidinone, sulfamides and sulfonamides aswell as mixtures thereof.

When the present electrolytic composition comprises more than onepolymer, at least one of those can be cross-linked.

An electrochemical generator comprising an electrolytic composition ofthe present invention preferably comprises a negative electrodecontaining either lithium metal or an alloy thereof, or a carboninsertion compound, in particular petroleum coke or graphite, or a lowpotential insertion oxide such as titanium spinel Li_(4-x+3y)Ti_(5-x)O₁₂(0≦x,y≦1), or a double nitride of a transition metal and lithium such asLi_(3-x)Co_(z)N (0≦z≦1) or having a structure of the antifluorite typelike Li₃FeN₂ or Li₇MnN₄, or mixtures thereof. The positive electrode ofthe generator preferably contains either vanadium oxide VO_(x)(2≦x≦2,5), a mixed oxide of lithium and vanadium LiV₃O₈, a double oxideof cobalt and lithium optionally partially substituted of generalformula Li_(1-α)Co_(1-x+y)Ni_(x)Al_(y)(0≦x+y≦1;0≦y≦0,3;0≦α≦1), amanganese spinel optionally partially substituted of general formulaLi_(1-α)Mn_(2-z)M_(z) (0≦z≦1) wherein M=Li, Mg, Al, Cr, Ni, Co, Cu, Ni,Fe; a double phosphate of the olivine or Nasicon structure such asLi_(1-α)Fe_(1-x)Mn_(x)PO₄, Li_(1-x-2α)Fe₂P_(1-x)Si_(x)O₄ (0≦x, α=1), arhodizonic acid salt, a polydisulfide derived from the oxidation ofdimercaptoethane, 2,5-dimercapto-1,3,4-thiadiazole,2,5-dimercapto-1,3,4-oxadiazole, 1,2-dimercaptocyclobutene-3,4-dione, ormixtures thereof.

Advantageously, at least one of the electrodes of the generator is mixedwith the electrolytic composition to form a composite electrode.

The electrolytic composition of the invention can also be used as anelectrolyte in an electrical energy storage system of the supercapacitytype, optionally containing, in an electrode, carbon with high specificsurface, or a conjugated polymer. Advantageously, the conjugated polymercomprises 3 degrees of oxidation, and is found in both electrodes. Anexample of such a polymer is a derivative of phenyl-3-thiophene.

Finally, the electrolytic composition of the invention can be used as anelectrolyte in a light modulating system of the electrochromic typecomprising as least one electrochromic material. In such a system, theelectrochromic material is advantageously deposited on a layer of asemi-conductor transparent in the visible, preferably a tin oxide orindium oxide derivative, on a glass or polymer substrate. Examples ofpreferred electrochomic materials include oxides of molybdenum,tungsten, titanium, vanadium, niobium, cerium, tin, and mixturesthereof. The electrochromic material can optionally be dissolved in theelectrolyte.

The following examples are provided to illustrate preferred embodimentsof the present invention, and should not be construed as limiting itsscope.

EXAMPLE 1

15 g of 1-methyl-3-ethyl imidazolium chloride EMICl (C₆H₁₁N₂Cl) aredissolved in 100 ml of water to which are added 23 g of potassiumbis-fluorosulfonimidide (KFSI) K[(FSO₂)₂N]. A separation in two liquidphases is immediately obtained. The molten salt of 1-methyl-3-ethylimidazolium bis-fluorosulfonimidide (EMIFSI) is extracted withdichloromethane and dried with anhydrous magnesium sulfate. Thesuspension is filtered and the solvent evaporated. The salt is driedunder vacuum at 80° C., and corresponds to the developed formula:

This ionic compound examined under DSC presents a melting point of −15°C. The weight loss measured by differential thermal analysis (DTA) underargon is lower than 1% up to 350° C. The conductivity and the functionof the temperature are provided in Table 1 below.

TABLE 1 Temperature (° C.) −10 0 10 20 30 40 50 60 Conductivity (mScm⁻¹)5.6 8.3 11 15 20 25 31 37 σ (FSI)/σ TFSI (%) 2.41 2.21 2.01 1.86 1.801.70 1.67 1.64

The conductivity is higher than that obtained with the 1-methyl-3-ethylimidazolium bis-trifluoromethanesulfonimidide salt (EMITFSI). The ratiobetween the conductivity values σ between the salt of the invention,i.e., 1-methyl-3-ethyl imidazolium fluorosulfonimidide (noted FSI in thetable) and 1-methyl-3-ethyl imidazoliumbis-trifluoromethanesulfonimidide (noted TFSI in the table) is given inthe last line of Table 1. These numbers show the significant improvementin the performances of the conductivity with respect to the prior art.

The electrochemical stability domain measured by cyclic voltammetry on anickel electrode for cathodic potentials in vitreous carbon for anodicpotentials is 5.2 Volts (05.2 V vs. Li⁺/Li°).

EXAMPLE 2

Lithium bis-difluorophosphonylamidide Li[(POF₂)₂N] is prepared accordingto the method of Fluck and Beuerle in Z. Anorg. Allg. Chem., 1975, 412,65, by reacting the lithiated derivative of hexamethyldisilazane onphosphorus oxyfluoride according to the following reaction:2 POF₃+Li[Si(CH₃)₃]₂N2 FSi(CH₃)₃+Li[(POF₂)₂N]

The molten ionic salt 1-methyl-3-ethyl imidazoliumbis-difluorophosphonylamidide is prepared by ionic exchange in wateraccording to Example 1 between 10 g of 1-methyl-3-ethyl imidazoliumchloride and 13 g Li[(POF₂)₂N] and extraction with dichloromethane. Themolten salt has physical/chemical properties similar to that of thefluorosulfonyl of Example 1.

EXAMPLE 3

Different imidazolium salts of general formula:

have been prepared with anions [(FSO₂)₂N]⁻ and [(POF₂)₂N]⁻, and areillustrated in Table 2 below. Those with the sign “+” are liquid saltsat room temperature.

TABLE 2 R³ = CH₃ C₂H₅ C₃H₇ C₄H₉ C₅H₁₁ C₇H₁₅ C₈H₁₇ R¹ = CH₃, R² =H + + + + + + R¹ = CH₃, R² = CH₃ + + + + + R¹ = C₂H₅, R² =H + + + + + + + R¹ = CH₃, R² = C₃H₃ + + + + + + +

EXAMPLE 4

10 g of commercial ammonium triethylhexyl bromide (C₁₂H₂₈NBr) aredissolved in 150 ml of water to which are added under agitation 8.5 g ofpotassium bisfluorosulfonimidide [K(FSO₂)₂N]. The molten salttriethylhexyl ammonium bisfluorosulfonimidide is separated bycentrifugation and washed with three aliquots of 50 ml of water andextracted with 30 ml of dichloromethane and dried with anhydrousmagnesium sulfate. The suspension is filtered and the solventevaporated, leaving a viscous liquid. The conductivity at 25° C. ishigher than 5×10⁻⁴ Scm⁻¹ at 25° C.

EXAMPLE 5

10 g of commercial dimethylethylamine and 11 ml of bromo-1-propane arerefluxed in 40 ml of acetonitrile for 48 hours. The solvent is thenevaporated and the solid residue is washed with ether. To 12 g of thesalt (CH₃)₂(C₂H₅)(C₃H₇)NBr dissolved in 75 ml of water are added 13 g ofpotassium bis-fluorosulfonimidide [K(FSO₂)₂N]. The molten salt isextracted as above to give a liquid of low viscosity. Its conductivityin view of various temperatures is provided in Table 3 below.

TABLE 3 Temperature (° C.) 20 30 40 50 Conductivity (mScm⁻¹) FSI  4.95 7.02  9.4 12.3  TFSI  1.81  2.92  4.3  6.1

For comparison purposes, the conductivity of thedimethylethylpropylammonium bis-trifluoromethanesulfonimidide salt isgiven (Table 3, line 3). The conductivity of the compound of theinvention is from about 2.5 to 2 times higher than that of theequivalent salt having a bigger anion.

EXAMPLE 6

N-methyl-N-ethyl-aniline is quaternized by bromopropane under reflux inacetonitrile for 48 hours. The salt is obtained by evaporation of thesolvent and purified by washing the solid residue with ether. 5 g of thesalt obtained are dissolved in 25 ml of water, and 4.6 g of potassiumbis-fluorosulfonimidide (K(FSO₂)₂N) are added. The molten saltmethylethylpropylphenyl ammonium bis-fluorosulfonimidide is extractedwith 15 ml of dichloromethane, washed with three aliquots of 50 ml ofwater and dried with anhydrous magnesium sulfate. The salt exists undertwo optical isomers that can be separated on a chiral column or byprecipitation of the camphor-sulfonate salt with bromide before exchangewith the imidide. The salt can be used in a chiral reactional media.

EXAMPLE 7

N-butylpyridinium bromide is prepared by reacting bromobutane onpyridine in the absence of a solvent at 45° C. To 5 g of this saltdissolved in 35 ml of water are added 4.6 g of lithiumbis-difluorophosphonylimidide Li[(POF₂)₂N]. The liquid salt is treatedin a manner similar to that of the molten salt obtained in the aboveexamples and is finally dried under vacuum at 60° C. The molten salt ofN-propyl pyridinium bis-fluorosulfonimidide is prepared in a similarmanner from the corresponding potassium salt.

EXAMPLE 8

Commercial ethylmethyl sulfide (Aldrich) is quaternized by propylsulfate (TCI). Diethylmethylpropylsulfonium propylsulfate is treated inan aqueous solution with one equivalent of potassiumbis-fluorosulfonimidide. The molten salt is extracted as above. In amanner similar to that described in Example 4, the salt can be separatedinto two optically active isomers and used to induce an enantiomericexcess for reactions performed when the salt is used as a solvent.

EXAMPLE 9

15 g of commercial 4-chloropyridine chlorhydrate are dissolved in 100 mlof water to which are added 8.5 g of sodium bicarbonate. The4-chloropyridine is extracted with ether and dried with magnesiumsulfate, and the solvent is evaporated. 10 g of 4-chloropyridine in 60ml of acetonitrile are quaternized by 15.6 g of ethyltrifluoromethanesulfonate and 11.6 g of trimethylsilylethylmethyl-amineC₂H₅(CH₃)NSi(CH₃)₃ are added. The reaction medium is refluxed for anhour, then cooled. The solvent is evaporated and the solid residual isplaced in water. To this solution are added 19.5 g of potassiumbis-fluorosulfonimidide. The decanting liquid salt is extracted withdichloromethane. The salt has the following structure:

EXAMPLE 10

Fluorosulfonamide FSO₂NH₂ is prepared by reacting fluorosulfonicanhydride (15 g) with ammonium carbamate (12 g) in suspension indichloromethane according to the following reaction:(FSO₂)₂O+1,5H₂NCO₂(NH₄)FSO₃(NH₄)+1,5CO₂+FSO₂NH(NH₄)

The reaction medium is filtered. The amide FSO₂NH₂ is freed by dilutedhydrochloric acid and extracted with ether. The trimethylsilylatedderivative of the sodic derivative of the fluorosulfonamide is preparedaccording to the method of Foropoulous et al. in Inorganic Chem., 1984,23, 3720. In a Parr® reactor, 80 ml of anhydrous acetonitrile are mixedwith 10 g of the fluorosulfonamide derivative. The reactor is closed andpurged under nitrogen, and 5.38 g of phosphoryl fluoride POF₃ are addedwhile maintaining the temperature at 45° C. The pressure falls after anhour and the reactor is cooled and opened. The sodium salt of the mixedimide is obtained according to the reaction:NaNSi(CH₃)₃SO₂F+POF₃Si(CH₃)₃+Na[(F₂PO)(FSO₂)N]

The salt is recovered by evaporation of the solvent andrecrystallization in a toluene-acetonitrile mixture. This salt givesliquid ionic derivatives with the imidazolium of Example 3, and showsliquid domains wider than that of the bis-trifluoromethanesulfonimidideand a conductivity higher by 10 a 25%.

EXAMPLE 11

25 ml of a commercial solution of diallyldimethyl-ammonium chloride(65%) in water are diluted with 100 ml, and 22 g of potassiumbis-fluorosulfonimidide are added under agitation. The liquidprecipitate is extracted with dichloromethane and dried with magnesiumsulfate. This molten salt has the following formula:

It behaves like a monomer active in radicalar polymerisation to form,through cyclopolymerization, dimethylpyrrolidinium bis(3,5-methylene-)patterns. This compound gives, in addition to homopolymers, copolymerswith styrene, maleic anhydride, N-maleimides, vinylidene fluoride,acrylonitrile, methacrylonitrile, methyl methacrylate, acrylates ormethacrylates of ω-methoxyoligo ethylene glycols of weight comprisedbetween 200 and 2000 daltons, eventually cross-linked with a diacrylateor methacrylate of α, ω-oligo ethylene glycol.

EXAMPLE 12

5 g of phosphorous pentachloride are dissolved in 50 ml dichloromethanein a flask comprising a bromine funnel and a dry argon entrance. Themixture is cooled with dry ice at −78° C. and 20 ml of methylethylaminein 30 ml of anhydrous acetonitrile are added drop wise through thebromine funnel. The reaction medium is maintained under agitation for anhour until room temperature is reached. The solvent is then evaporatedand the residue is washed with 75 ml of water and filtered on Celite®.To this solution are added 5.5 g of potassium bis-fluorosulfonimidide.The reaction medium separate into two liquid phases. The molten salt oftetrakis(ethylmethylamino)phosphonium {P[N(CH₃)(C₂H₅)]₄}⁺[(FSO₂)₂N]⁻ isan oily liquid at room temperature. This molten salt is particularlystable towards reducing or nucleophilic agents, even at hightemperatures.

EXAMPLE 13

20 g of a commercial aqueous solution of 25% ofpoly(diallyldimethylammonium) chloride of high molecular weight (M_(W)about 2×10⁵) are diluted in 100 ml of water. Under magnetic agitationare added 6.7 g of potassium bis-fluorosulfonimidide in 100 ml of water.The precipitate of poly(diallyldimethylammonium bis-fluorosulfonimidide)

is then filtered and washed abundantly with distilled water, then driedunder vacuum.

EXAMPLE 14

A liquid electrolyte is obtained by dissolving lithiumbis-trifluoromethanesulfonylimidide (LiTFSI) in a 1 molar concentrationin the molten salt prepared in Example 1. Conductivity of this mixtureis 9×10⁻³ Scm⁻¹ at 25° C., and remains higher than 2×10⁻³ Scm⁻¹ at 0° C.The anodic domain found by cyclic voltammetry is superior to 5V/Li°/Li⁺.

EXAMPLE 15

A solid electrolyte is obtained by plasticization of the polyelectrolyteof Example 13 with a solution of the lithium salt in the imidazolium ofExample 14. To mold this electrolyte, the 3 components(polyelectrolyte-FSI, imidazolium-FSI, LiTFSI) are weighted according tothe following ratios: polyelectrolyte (40% by weight); LiTFSI, 1 M inthe imidazolium salt (60% by weight). The three components are dissolvedin a volatile polar solvent, such as acetonitrile, the amount of solventbeing adjusted to allow spreading of the solution as a thin film to giveafter drying a thickness of 35 μm on a polypropylene support.

The film thus obtained is dried by dry air, then placed under a primaryvacuum at 100° C. for 2 hours. All further handling of this film aremade in a glove box (<1 ppm O₂ and H₂O). The conductivity of thiselectrolyte is equal to 10⁻³ Scm⁻¹ at 20° C.; 4×10⁻⁴ Scm⁻¹ at 0° C.; and3×10⁻³ Scm⁻¹ at 60° C. Electrolytes with higher conductivity can beobtained by raising the fraction of the plasticizer (>60%), i.e., thesolution of LiTFSI of the molten salt of Example 1. In a similar manner,higher elasticity modules are obtained for plasticizers fractions <50%with a reduction in conductivity.

EXAMPLE 16

A polymer electrolyte of high conductivity is obtained by plasticizing ametallic salt-polyether complex with 40% by weight of an anioniccompound of Example 2. The complex comprises lithiumbis-trifluoromethanesulfonimidide of poly(ethylene oxide) of molecularweight 5×10⁶, in a manner such that the ratio of the oxygen atoms of thepolymer versus the number of lithium ions is equal to 20 (O: Li=20:1).The electrolyte can be prepared directly by co-dissolving the componentsweighted according to the stoichiometric proportions in a solvent suchas acetonitrile, and evaporation followed by drying under vacuum at 80°C.

In a variation, the ethylene oxide homopolymer can be replaced with acopolymer of ethylene oxide and allylglycidylether (5% molar) to whichare added 1% by weight of Irgacure 651®. The solution in acetonitrile isspreaded on a polypropylene support to form a film of a thickness of 20microns after drying. Under argon sweeping, the film is submitted to UVrays produced by a Hanovia® type lamp having its maximum of emission at254 nm. The illumination corresponds to an energy of 130 mWcm⁻². Thepolymer cross-links through a radicalar process by the unsaturatedsegments and shows excellent elastomeric-type mechanical properties.Ternary mixtures molten salt/lithium salt/polymer can be obtained in asimilar manner with, as the macromolecular material, acrylonitrile;polyvinylidene fluoride and its copolymers with hexafluoropropene, inparticular those soluble acetone and easily embodied; or methylpolymethacrylate.

EXAMPLE 17

A polymer electrolyte is prepared by polymerisation in situ of a mixtureof the monomer of Example 11 (25% by weight), lithiumbis-trifluoromethanesulfonimidide (24%) and the molten salt of Example 1(45%), and 1% of the radical initiator

This initiator is obtained by exchange in water from the commercialchloride (Wako) and K(FSO₂)₂N). The liquid mixture is spreaded in theform of a film of a thickness of 30 microns on a polypropylene support,and polymerized in a tunnel oven under nitrogen atmosphere at 80° C. for1 hour. The electrolyte thus obtained is an elastomer having an anodicstability domain higher than 5V and a conductivity greater than 3×10⁻⁴Scm⁻¹ at 25° C.

EXAMPLE 18

A secondary electrochemical generator is manufactured with a doubleoxide of cobalt and lithium LiCoO₂ as the active material for thepositive electrode, and titanium and lithium spinel Li₄Ti₅O₁₂ as theactive material for the negative electrode. The electrolyte is preparedaccording to Example 14 in the form of a 25 microns film. Each electrodeof the composite type is prepared by spreading a suspension of theactive material carbon black (Ketjenblack®) in a solution of a copolymerethylene-copropylenediene (Aldrich) in cyclohexane. The finalcomposition corresponds to 90% by volume of active material, 5% v/v ofcarbon black and 5% of copolymer. After spreading on aluminium currentcollectors of a thickness of 8 microns, the negative electrode contains16.4 mg of active material per cm², (2.9 mAhcm⁻²), and the positiveelectrode 16.5 mg of active material per cm², (2.7 mAhcm⁻²). Theelectrodes and the current collectors are cut in squares of 4 cm² andplaced on each side of a microporous polyethylene membrane (Celgard®)wetted with the liquid electrolyte prepared in Example 14. The batterythus assembled is characterized by slow voltammetry with a MacPile® typeapparatus (Claix France). 92% of the capacity of the positive electrodeis obtained in the voltage domain 2-2.8 V at a sweeping speed of 10mV.mn⁻¹. The energy density in this configuration is 85 Wh.kg⁻¹.

EXAMPLE 19

A secondary electrochemical generator is manufactured with the doublephosphate of iron-doped manganese and lithium LiMn_(0,9)Fe_(0,1)PO₄, asthe active material of the positive electrode, and titanium and lithiumspinel Li₄Ti₅O₁₂ as the active material for the negative electrode. Theelectrolyte is prepared according to Example 15 in the form of a film ofa thickness of 25 microns. Each electrode of the composite type isprepared by spreading a suspension of 45% by volume of the activematerial, 5% v/v of carbon black (Ketjenblack®) and a solution of thecomponents of the electrolyte according to Example 12 (50% v/v) inacetonitrile. The aluminium current collectors have a thickness of 8microns. The positive electrode collector is covered with a protectivecoating of graphite (Acheson). After spreading, the negative electrodehas a charge of 12 mg of active material per cm² (2.2 mAhcm⁻²) and thepositive electrode 14 mg of active material per cm² (2.4 mAhcm⁻²). Theelectrodes and the current collectors are cut in squares of 4 cm² andplaced on each side of the electrolyte and the assembly is laminated at80° C. to ensure a good contact at the interfaces. The battery thusassembled is characterized by slow voltammetry. 82% of the capacity ofthe positive electrode are obtained in the voltage domain 2.6-3.2 V at asweeping speed of 10 mV.mn⁻¹. The energy density in this configurationis close to 100 Wh.kg⁻¹.

EXAMPLE 20

A supercapacity is obtained from electrodes of activated carbon fibersof 900 m²g⁻¹ (Spectracarb®). Two squares of 4 cm² are cut in the carbonfabric and wetted under vaccum with the electrolyte prepared inExample 1. Both symmetrical electrodes are separated with a porouspolyethylene membrane (Celgard®) wetted under vacuum by the same ionicliquid. Both collectors of current are in aluminium of 10 μm coated bycathodic spraying of protective layer of 5000 Å of molybdenum. Thevolumic capacity for a maximum charge tension of 2.8 V is 12 Fcm⁻³, (3Wh.L⁻¹) at the threshold tension cut of 1.2 V.

EXAMPLE 21

The imidazolium salt of Example 1 is used as a solvent of yttriumbis-trifluoromethanesulfonimidide in concentration of 0.1M. This liquidis used as a catalyst in a Diels-Alder reaction of cyclopentadiene withmethyl acrylate. The reagents are mixed in stoichiometric quantities,and 30% v/v of the ionic liquid are added. Under agitation, the reactionis completed in 1 hour at 25° C. The reaction products are extractedwith hexane, which is non-miscible with the ionic compound. The ratioendo/exo is 9:1. The catalyst treated at 100° C. under vacuum can bereused without loss of activity.

EXAMPLE 22

The molten salt prepared in Example 12 is used as a solvent fornucleophilic substitution reactions. 10 g of that salt and 3 g ofpotassium cyanide are put in a glass tube in an oven and the temperatureis raised to 250° C. 4 g of benzyl chloride are heated at 60° C. for 2hours. The yield of conversion of the benzyl chloride into benzylcyanide is 85%. The molten salt can be easily recycled by washing withwater and evaporation.

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications, and this application is intended to cover any variations,uses or adaptations of the invention following, in general, theprinciples of the invention, and including such departures from thepresent description as come within known or customary practice withinthe art to which the invention pertains, and as may be applied to theessential features hereinbefore set forth, and as follows in the scopeof the appended claims.

1. An ionic compound having a cation of the onium type with at least oneheteroatom comprising N, O, S or P bearing the positive charge and theanion including, in whole or in part, at least one imide ion at the type(FX¹O)N−(OX²F) wherein X¹ and X² are the same or different and compriseSO or PF, wherein the compound comprises at least an anion selected fromCl⁻; Br⁻; I⁻; NO₃ ⁻; M(R¹⁰)₄ ⁻; A(R¹⁰)₆ ⁻; R¹¹YO₂ ⁻; R¹¹YONZ¹⁻;R¹¹YOCZ²Z³; 4,5-dicyano-1,2,3-triazole; 3,5-bis(R_(F))-1,2,4-triazole;tricyanomethane; pentacyanocyclopentadiene;pentakis(trifluoromethyl)cyclopentadiene; and barbituric acid, and; M isB, Al, Ga or Bi; A is P, As and Sb; R¹⁰ is a halogen; R¹¹ represents H,F, alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl, alkenylaryl,dialkylamino, alkoxy or thioalkoxy, each having from 1 to 18 carbonatoms and being unsubstituted or substituted with one or more oxa, thia,or aza substituents, and wherein one or more hydrogen atoms areoptionally replaced with halogen in a ratio of 0 to 100%, and eventuallybeing part of polymeric chain; Y represents C, SO, S═NCN, S═C(CN)₂,PR¹¹, P(NCN)R¹¹, P(C(CN)₂)R¹¹, and when Y is P(NCN)R¹¹ or P(C(CN)₂)R¹¹,then R¹¹YO₂, R¹¹YONZ¹, and R¹¹YOCZ²Z³ become R¹¹YO, R¹¹YNZ¹, andR¹¹YCZ²Z³, respectively, an alkyl, alkenyl, aryl, arylalkyl, alkylaryl,arylalkenyl, alkenylaryl having from 1 to 18 carbon atoms and optionallysubstituted by one or more oxa, thia or aza; a dialkylamino groupN(R¹¹)₂; Z¹, Z², and Z³ represent independently R¹¹, R¹¹YO or CN, thisgroup being optionally part of a polymeric chain.
 2. A method of usingelectrolytic composition, comprising the step of: carrying out chemicalor electrochemical reactions involving soluble species in a mediumcomprising said electrolytic composition, wherein said reactions areselected tram Diels-Alder, Friedel-Craft, mixed aldolization,condensation, polymerization, nucleophilic substitution, andelectrophilic substitution reactions, and where in said electrolyticcomposition comprises at least one ionic compound of low melting pointhaving a cation of the onium type with at least one heteroatom selectedfrom N, O, S or P bearing the positive charge and the anion including,in whole or in part, at least one imide ion of the type (FX¹O)N⁻(OX²F),wherein X¹ and X³ are the same or different and comprise SO or PF. 3.The method according to claim 2, wherein the composition is used incombination with at least another component comprising a metallic salt,a polar polymer and/or an aprotic co-solvent.
 4. The method according toclaim 2, wherein the composition comprises a chiral onium cationallowing enantionselective reactions.
 5. A medium used to perform anorganic chemistry reaction involving soluble species present in saidmedium, comprising: at least one ionic compound of low melting pointcomprising a cation of the onium type having at least one heteroatomselected from N, O, S or P carrying a positive charge; and an anionincluding, in whole or in part, at least one imide ion of the type(FX¹O)N⁻(OX²F), wherein X¹ and X² are the same or different and compriseSO or PF, and wherein such medium is optionally used in combination withat least one other component selected from the group consisting of ametallic salt, a polar polymer, and an aprotic cosolvent, and whereinthe medium comprises at least one chiral onium cation allowingenantioselective reactions.
 6. A medium used to perform an organicchemistry reaction involving soluble species present in said medium,comprising: at least one ionic compound of low melting point comprisinga cation of the onium type having at least one heteroatom selected fromN, O, S or P carrying a positive charge; and an anion including, inwhole or in part, at least one imide ion of the type (FX¹O)N⁻(OX²F),wherein X¹ and X² are the same or different and comprise SO or PF. andwherein such medium is optionally used in combination with at least oneother component selected from the group consisting of a metallic salt, apolar polymer, and an aprotic cosolvent, and wherein the mediumcomprises at least one catalytic species.
 7. The medium according toclaim 6, wherein the catalytic species is at least one of the groupconsisting of an alkaline metal salt, a transition metal salt, a rareearth metal salt, and an organometallic salt.
 8. The medium according toclaim 7, wherein the catalytic species is coordinated with one or moreligands.
 9. The medium according to claim 7, wherein the organometallicsalt is a metallocene.
 10. The medium according to claim 8, wherein theone or more ligands are selected from the group consisting ofbipyridines, porphyrines, phosphines, and arsines.
 11. Anelectrochemical device having at least two electrodes and oneelectrolyte, said electrolyte comprising at least one ionic compound oflow melting point, comprising: a cation of the onium type with at leastone heteroatom selected from N, O, S or P carrying a positive charge;and an anion including, in whole or in part, at least one imide ion ofthe type (FX¹O)N⁻(OX²F), wherein X¹ and X² are the same or different andcomprise SO or PF, and wherein the electrolyte comprises at least oneanion [B] selected from the group consisting of Cl⁻; Br⁻; I⁻; NO₃ ⁻;M(R¹⁰)₄ ⁻; A(R¹⁰)₆ ⁻; R¹¹YO₂ ^(−; [R) ¹¹YONZ¹]⁻; [R¹¹YOCZ²Z³]⁻; (R¹¹)₂PO₂ ⁻; (R¹¹)₂P(NCN)O⁻; (R¹¹)₂P(C(CN)₂)O⁻; [(R¹¹)₂P(NCN)NZ¹]⁻;[(R¹¹)₂P(C(CN)₂)NZ¹]⁻; 4,5-dicyano-1,2,3-triazole;3,5-bis(Rf)-1,2,4-triazole; tricyanomethane; pentacyanocyclopentadiene;pentakis(trifluoromethyl)cyclopentadiene; barbituric acid; and Meldrumacid derivatives and their substitution products, wherein M is B, Al, Gaor Bi; A is P, As and Sb; R¹⁰ is a halogen; R¹¹ represents independentlyH, F, alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl,alkenylaryl, dialkylamino, alkoxy or thioalkoxy, each having from 1 to18 carbon atoms and being unsubstituted or substituted with one or moreoxa, thia, or aza substituents, and wherein one or more hydrogen atomsare optionally replaced with halogen in a ratio of 0 to 100%, andeventually being part of polymeric chain; Y represents C, SO, S═NCN,S═C(CN)2, an alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl,alkenylaryl having from 1 to 18 carbon atoms and optionally substitutedby one or more oxa, thia, or aza, or a dialkylamino group N(R¹⁰)₂; andZ¹ to Z³ represent independently R¹¹, R¹¹YO,(R¹¹)₂PO, (R¹¹)₂P(NCN),(R¹¹) ₂P(C(CN)₂) or CN, wherein this group is optionally part of apolymeric chain.
 12. The electrochemical device according to claim 11,wherein said device, is used as an electrochemical generator, saidgenerator comprising one negative and one positive electrode, whereinsaid one negative electrode comprises a compound selected from the groupconsisting of lithium or an alloy thereof, a carbon insertion compoundsuch as petroleum coke or graphite, a low insertion potential oxide (<2Volts vs Li⁺/Li⁰) such as titanium spinel Li_(4−x+3y)Ti_(5−x)O₁₂(0≦x,y≦1), a double nitride of a transition metal and lithium such asLi_(3−x)CO_(z)N (0≦z≦1), a compound having a structure of theantifluorite type such as Li₃FeN₂ or Li₇MnN₄, and mixtures thereof; andsaid one positive electrode comprises a compound selected from the groupconsisting of VO_(x)(2≦x≦2.5), mixed oxides of lithium and vanadium suchas LiV₃O₈; a double oxide of cobalt and lithium that is optionallypartially substituted by at least one cation M and has a general formulaLi_(1−α)Co_(1−x+y)Ni_(x)Al_(y)(0≦x+y≦1; 0≦α≦1), wherein M=Li, Mg, Al,Cr, Ni, Co, Cu, Ni, Fe, a double phosphate of the olivine or Nasiconstructure such as Li_(1−α)Fe_(1−x)Mn_(x)PO₄,Li_(1−x+2α)Fe₂P_(1−x)Si_(x)O₄(0≦x, α≦1), a rhodizonic acid salt, apolydisulfide derived from the oxidation of dimercaptoethane,2,5-dimercapto-1,3,4-thiadiazole-2,5dimercapto-1,3,4-oxadiazole-1,2-dimercaptocyclobutene -3,4-dione; andmixtures thereof.
 13. The electrochemical device according to claim 11,wherein the electrolyte comprises at least one salt of anion B with acation selected from the group consisting of a proton, a cation of analkaline metal, a cation of an alkaline-earth metal, a cation of atransition metal, and a cation of a rare earth metal.
 14. Theelectrochemical generator according to claim 13, wherein at least onesalt is a lithium salt.
 15. The electrochemical device according toclaim 11, wherein said device is used as an electrical energy storagesystem of the supercapacitor type.
 16. The electrical energy storagesystem according to claim 15, wherein at least one electrode comprisescarbon having a high specific surface area greater than 50 m²/gr. 17.The electrical energy storage system according to claim 15, wherein atleast one electrode comprises a conjugated polymer.
 18. The electricalenergy storage system according to claim 17, wherein both electrodescomprise a conjugated polymer having three degrees of oxidation.
 19. Theelectrical energy storage system according to claim 18, wherein theconjugated polymer is a phenyl-3-thiophene derivative.
 20. Anelectrochemical device having at least two electrodes and oneelectrolyte, said electrolyte comprising at least one ionic compound oflow melting point comprising: a cation of the onium type with at leastone heteroatom selected from N, O, S or P carrying a positive charge;and an anion including, in whole or in part, at least one imide ion ofthe type (FX¹O)N⁻(OX²F), wherein X¹ and X² are the same or different andcomprise SO or PF, and wherein the electrolyte is impregnated in aporous membrane.
 21. The electrochemical device according to claim 20,wherein the electrolyte is used in combination with at least anothercomponent comprising a metallic salt, a polar polymer and/or an aproticco-solvent.
 22. An electrochemical device as in claim 11 wherein theelectrolyte is impregnated in a porous membrane optionally incombination with at least another component comprising a metallic salt,a polar polymer and/or an aprotic co-solvent.
 23. The method accordingto claim 3, wherein the composition comprises a chiral onium cationallowing enantioselective reactions.